Repeating circuit interrupter having indexing means on the integrating piston



April 12, 1966 REPEATING CIRCUIT i Filed Feb. 17, 1964 K H. DATE NTERRUPTER HAVING INDEXING MEANS ON THE INTEGRATING PISTON 5 Sheets-Sheet l INVENTOR.

BY Kezzw F f Date Aprll 12, 1966 K. H. DATE 3,246,099

REPEATING CIRCUIT INTERRUPTER HAVING INDEXING MEANS ON THE INTEGRATING PISTON Filed Feb. 17, 1964 3 Sheets-Sheet 2 73 INVENTOR.

Kazuo ffi Date BY 3M WM' April 12, 1966 T 3,246,099

REPEATING CIRCUIT INTERBUPTER HAVING INDEXING MEANS ON THE INTEGRATING PISTON Filed Feb. 17, 1964 3 Sheets-Sheet 5 iii;

INVENTOR. Kazw H. in? BY United States Patent 3,246,099 REPEATING CIRCUIT INTERRUPTER HAVING INDEXING MEANS ON THE INTEGRATING PISTON Kazuo Henry Date, South Milwaukee, Wis., assignor to McGraw-Edison Company, Milwaukee, Wis., a corporation of Delaware Filed Feb. 17, 1964, Ser. No. 345,452 13 Claims. (Cl. 200-89) This invention relates to repeating circuit interrupters and, more particularly, to a hydraulic control mechanism for a repeating circuit interrupter.

It is common practice to utilize a variety of protective devices having time current characteristics of different shapes and slopes in a single electrical system. For example, distribution systems may be provided with a repeating circuit interrupter or recloser connected in series with a main line and located adjacent the source of power and fuses disposed in feeder lines radiating from the main line. Because the majority of faults in such systems are temporary in nature, and will therefore clear in a relatively short time, it is common to arrange the repeating circuit interrupter to execute a series of rapid opening and reclosing operations so that the period during which the system remains energized to shorter than the time necessary for the fuse elements to melt. If the fault does not clear during this initial series of rapid operations, it is considered permanent and there follows a second series of operations during which the recloser contacts remain closed for a period of sufiicient length to melt the fuse element in the faulted feeder line. If the fault clears upon the melting of the fuse element or for some other reasons during any of these successive operations, the recloser closes to maintain power in the main line and in the non-faulted feeder lines. If on the other hand the fault is not cleared during this series of rapid and retarded opening operations the recloser automatically locks out to disconnect the main line from the source. In order to properly coordinate a particular recloser with other protective devices, the number of opening operations prior to lockout must be conveniently and accurately preselectible.

One type of prior art repeating circuit interrupter utilizes hydraulic operation counting means which is operable after a predetermined number of switch opening operations to prevent reclosure of the device. The op .eration counting means also performs the function of initiating retarded switch opening operations of the recloser after a plurality of rapid operations. Such hydraulic mechanisms generally include a pump piston designed to deliver a measured quantity of fluid to a counting piston upon each switch opening operation. Each such pumping operation advances the integrating piston a predetermined distance toward a tripping member which is operative to release the switchs main contacts and prevent reclosure thereof. If the fault disappears before the requisite number of operations, the integrating piston settles to its initial position whereby the device is reset in preparation for another series of operations. It can be seen, however, that some resetting of the integrating piston will also occur between interrupting operations. In some applications the time between reclosing operations of the recloser is relatively long and this resetting of the integrating piston creates a serious problem because if the rate of resettlement is too rapid the device cannot retain its count for the desired length of time and if this rate is too slow the device cannot be rapidly reset.

It is an object of the invention to provide a new and improved hydraulic integrating assembly for repeating circuit interrupters.

Another object of the invention is to provide a hydraulic integrating assembly for repeating circuit interrupters wherein there is no resettlement when overload current flows in the system but wherein the device may be rapidly reset after the disappearance of overload current.

A more specific object of the invention is to provide means for holding the integrating piston of a hydraulic operation counting device in its advanced positions during periods when the circuit interrupters main contacts are closed and a fault exists in the system and for releasing the piston for advancement when the main contacts are tripped open.

Yet another object of the invention is to provide new and improved means for controlling the initiation of time delayed operations of a hydraulic repeating circuit interrupter.

Another specific object of the invention is to provide a repeating circuit interrupter having hydraulic time delay means and integrating means having a first and second plurality of indexing means and an indexing member engageable with the first plurality of indexing means during initial switch opening operations and the second plurality of indexing means during subsequent opening operations wherein the indexing member is operative to impede egress of hydraulic fluid from the hydraulic time delay means when engaging the first plurality of indexing means. According to another object of the invention, the engagement between the indexing member and the indexing means prevents settlement of the integrating means.

These and other objects and advantages of the instant invention will become more apparent from the detailed description thereof taken with the accompanying drawings in which:

FIG.1 is a side elevational view, with parts broken away, of a repeating circuit interrupter incorporating the instant invention;

FIG. 2 is a view taken along lines 2-2 of FIG. 1;

FIG. 3 is a view taken along lines 33 of FIG. 2;

FIGS. 4 and 5 illustrate the operation of the integrating mechanism according to the instant invention; and

FIG. 6 illustrates an alternate embodiment of the instant invention.

Referring now to the drawings in greater detail, FIG. 1 shows a repeating circuit interrupter 10 incorporating the instant invention and including a metallic housing or tank 11 which is closed at its upper end by a gasketed cover 13 from which the internal operating mechanism is suspended on insulating stringers 14. The tank 11 is ordinarily filled with dielectric fluid, such as oil, to the level indicated by the dashed line 15.

The cover 13 also supports a pair of insulating bushings 16, only one of which is shown in FIG. 1. The bushings 16 extend interiorly of the tank 11 and beneath the oil level 15 for serially connecting the recloser 10 in the system being protected. As seen in FIG. 1, the current path between the bushings 16 and through the recloser 10 constitutes a series circuit including an electromagnetic operating coil 17 and an interrupting switch generally designated by the reference numeral 18.

In order to correlate the various portions of the repeating circuit interrupter 10 shown in FIG. 1, its operation will now be discussed in general terms. Each time an overcurrent occurs in the system being protected, an electromagnetic plunger 19 is attracted downwardly into the series connected operating coil 17 to move an operating rod 20 connected to its lower end into engagement with an overcenter operating mechanism 24 of the interrupter switch 18, causing the movable contact arm 21 to pivot around pin 26 in an open position. When the in- 3 terrupting contacts 18 open, the series coil 17 is de-energized so that the overccnter mechanism 24 elevates the electromagnetic plunger 19* to rotate the contact arm 21 counterclockwise into its closed position.

Although the details of the overcenter mechanism 24 form no part of the instant invention, its operation will now be briefly described so that the operation of those portions of the repeating circuit interrupter which comprises the instant invention can be more easily understood. As seen in FIG. 1, the lower end of the rod 29 rests on a roller 99 carried on one end of a lever 100, the other end of which is pivotally mounted about a pin 101. A long link 162 is connected at one end of the lever 100 and extends downwardly therefrom where its opposite end is connected by a pin to one end of a short link 1&5 whose other end is provided with an elongate slot 103 which slidably engages a fixed pin 104. An overcenter spring 106 extends between a pin 1tl7 carried intermediate the ends of link 102 and bracket member 108 extending upwardly from the contact arm 21. In addition, a link 110 pivotally mounted at 111 is coupled to the pin 1G7.

When the circuit interrupter is in its closed position shown in FIG. 1, the spring 106 exerts an upward force on link 162 to hold plunger 19 in its elevated position. When an overload current traverses coil 17 to attract plunger 19 downwardly, link 1% is rotated clockwise as viewed in FIG. 1 to force links 182 and 195 downwardly as the link 110 pivots counterclockwise to swing pin 107 in an are about point 11. This action continues until the roller 99 impacts a second roller 112, carried by the bracket member 198, to pivot the switch arm 21 clockwise. Simultaneously, the line of action of spring 1% moves past the pivotal axis of switch arm 21 whereupon the switch arm is snapped counterclockwise opening the interrupting contacts 18.

If the plunger 19 is not restrained in its downward position after the disappearance of the current in coil 17, the overcenter spring 106 will tend to move the links 1112 and 105 upwardly, thereby elevating the plunger 19. This will continue until the upward movement of pin 107 brings the line of action of spring 196 past the pivotal axis of switch arm 21 whereupon the switch arm will again be in an overcenter position and will snap into its closed position shown in FIG. 1.

As will be described more fully hereinbelow, each time the magnetic plunger 1% is returned to its elevated position upon the reclosure of the interrupting contacts 18 an insulating stem 22 connected to its upper end is operative through the agency of a pair of slotted links 23 to depress a pump piston 25 to thereby deliver a measured quantity of hydraulic fluid to a hydraulic integrating mechanism 27. Upon each such pumping operation, a stem 28 extending outwardly from the in tegrating mechanism 27 is adavnced a predetermined distance toward a trip finger 29. After a predetermined number of such switch opening and reclosing operations, the stem 28 will engage the finger 29 to release the overcenter lockout mechanism 3! which is connected to the upper end of the stem 22 and which upon being released is operative to depress the magnetic plunger 19 and thereby open the main interrupting contacts 18 and hold the same open until manually reset.

The magnetic circuit for the flux emanating from the coil 17 includes the plunger 1?, a metallic head casting 31, a metallic base plate 32 and metallic bracket members 33 on support rods 34 with which extend between the head casting 31 and the plate 32. The bracket members 33 along with the rods 34 serve to support the coil 17 and the base plate 32 which, in turn, supports the interrupting switch 18.

Certain of the various details of the repeating circuit interrupter just discussed from no part of the instant invention and, accordingly, will not be discussed in detail for the sake of brevity. For a more complete description of these details, reference is made to Patent 2,926,228 which is assigned to the assignee of the instant invention.

As seen more particularly in FIG. 3 the magnetic plunger 19 descends through a bore 35 formed in a head casting 31 which also contains the pump piston 25 and the integrating assembly 27. A dashpot cylinder 37 is disposed coaxially with the bore 35 for receiving the magnetic plunger 19 and is formed by the insulating spool 38 upon which the series operating coil 17 is wound As aperture (not shown) is provided on the lower end of dashpot cylinder 37 to allow the operating rod 2% to pass therethrough for engagement with the overcenter assembly 24- as discussed hereinabove.

The pump piston 25 is disposed for reciprocal movement within a cylinder 40 formed in the casting 31 and has a stem 41 extending upwardly for pivotal engagement with one end of the link 23. An elongate slot 43 is formed in the other end of link 23 for engagement with a pin 44 extending transversely from the magnetic plunger stem 22.

The lower end of cylinder 40 is connected by a semicircular duct 48 formed in the bottom of the head casting 31 (see FIG. 2) with the lower end of an integrating cylinder 50 which is a part of the integrating mechanism 27 The duct 48 is sealed by a flat gasket 51 held against the lower end of the head casting 31 by a circular washer plate 52 which is disposed between the spool 38 and the head casting 31 and which has an aperture 53 for passage of the magnetic plunger.

The integrating assembly 27 includes an integrating piston 54 disposed within the cylinder 59 and consisting of a plurality of large diameter beveled washers 55, a plurality of small diameter beveled washers 56 and a pair of base Washers 57, all of which are mounted at the lower end of the stem 28 as seen in FIG. 3. The purpose of the various size washers 55 and 56 will be discussed more fully hereinbelow, it being suflicient at this point to state that the outer diameter of the washers 55 and 57 is substantially equal to that of the cylinder 59 so that they act as a piston therein. A return spring 58 surrounds the stem 28 and acts to resist upward movement of the piston 54.

Downward movement of the magnetic plunger 19 upon the occurrence of an overcurrent through coil 17 will pivot link 23 counterclockwise about fixed pivot point as viewed in FIG. 3, thereby elevating pump piston 25 in cylinder 40. This draws the oil Within tank 11 past a ball checkvalve 47 and into the lower end of the cylinder 40. When the magnetic plunger 19 returns to its elevated position upon the closing of the main interrupting contacts, link 23 will pivot clockwise about point 45 to depress the pump piston 25 into the cylinder 4s. Upon the initial descent of the piston 25 the hydraulic fiuid in the lower end of cylinder 40 will be discharged through a relief orifice 62 and this will continue until the lower end of the piston 25 has been depressed sufficiently to cover this orifice. Thereafter, as the piston 25 descends the fluid in the lower end of cylinder 40 will be delivered to the lower end of the cylinder 5% through the duct 48 and past a ball checkvalve 59.

The integrating assembly 27 also includes a slide valve assembly 66 which is disposed within an elongate cylindrical duct 61 formed in the head casting 31 and extending transversely of the integrating cylinder 50. The slide valve es consists of a pair of cylindrical piston valves 63 and 64 which are slidable within the duct 61 and which are carried in spaced apart relation on an elongate stem 66. The inner end of the duct 61 communicates with the integrating cylinder through an aperture 68 so that the inner end of the stem 66 can be moved into engagement with the annular grooves 70 provided between coacting adjacent washers or 56.

The outer end of the stem 66 extends outwardly of the head casting 31 through the end of the duct 61 and pivotally engages one end of a magnetic clapper 72 the the unobstructed outer end of duct 61.

other end of which is pivotally mounted on one end of a pole piece 73 mounted on the base plate 32 and terminating short of the head casting 31 to provide an air gap which is oriented to receive stray flux from the main operating coil 17. A spring 76, circumjacent the inner end of the stem 66, holds the magnetic clapper 72 away from the head casting 31 and urges the slide valve 69 outwardly of the duct 61 but such movement is prevented by a stop washer 78.

As seen in FIGS. 2 and 3 an annular groove 79 is formed in the lower end of the bore 35 and is connected by a passage 80 to the lower end of a vertical relief duct 81 formed in the head casting 31. A second vertical relief duct 82 is formed in the head casting 31 in parallel with the duct 81 and is connected thereto by a transverse passage 83, the outer end of which is closed by a safety valve 84. The outer ends of ducts 81 and 82 are covered by the orifice plate 85 having a plurality of various sized orifices 36 which may be moved into registry with the outer ends of the ducts 81 and 82 to control the discharge of fluid therefrom. Adjustment of the orifice plate 35 is accomplished by loosening a screw 87 which secures the plate 85 to the casting 31.

When the clapper 72 is in its unattracted position, the slide valve member 63 will lie at the intersection of the ducts 61 and 81 to prevent the discharge of fluid from the outer end of duct 81. Also, the second slide valve member 64 will be disposed to one side of the duct 82 so that the outer end thereof will be vented through orifice 8651.

Upon the occurrence of an overcurrent in the system being protected, the plunger 19 will be attracted downwardly into the dashpot 37 and at the same time the clapper 72 will be attracted clockwise as seen in FIG. 4, by the magnetic leakage flux so that the slide valve 60 will be moved .to the right until its inner end engages a 'groove 70 formed between a pair of small diameter washers 56. As a result of this movement, slide valve 60 will be in its position shown in FIG. 4 wherein the first slide valve member 63 moves out of blocking engagement with the outer end of duct 81 and in addition the second slide valve member 64 moves between the outer ends of ducts 81 and 82. Thus, the hydraulic fluid discharging from the dashpot 37 as a result of the descent of the plunger 19 will be free to flow through the duct 81 and out of the orifice 86a, through the ducts 83 and 82 and out of the orifice 86b and, in addition, through As a result, plunger 19 is free for relatively rapid descent of the dashpot 37 so that the recloser contacts will open rapidly.

The descent of plunger 19 will also pivot link 23 counterclockwise about pivot point 45 to thereby elevate the pump piston 25 in the pump cylinder 40. As

discussed hereinabove, when the plunger 19 reaches its lowermost position in the dashpot 37 the reclosers main contacts will be open to deenergize the coil 17 and thereby release the plunger 19 for upward movement to its initial position and also to release the clapper 72 for counterclockwise movement to its initial position under the influence of spring 76.

The return movement of the plunger 19 is operative to depress pump piston 25 in the cylinder 40 whereby a measured quantity of hydraulic fluid is delivered beneath the integrating piston 54 whereby the latter is raised in the cylinder 50 and against the return spring 58. This elevates the integrating piston 54 to the point where the lowermost of the annular grooves 70 between the small diameter washers is opposite the inner ends of .the slide valve rod 66.

When the plunger 19 reaches its initial position, the main contacts will reclose. Should the fault have cleared during this initial opening operation, the return spring 58 will be free to return the integrating piston 54 to its initial position in preparation for another series of switch opening operations. However, should the fault reappear the plunger 19 will again be immediately attracted downwardly while the clapper 72 will again move the slide valve rod 66 toward the right until it engages the groove 70 between the lowermost two of the small diameter washers 56. As a result the plunger 19 will again descend rapidly for a rapid opening operation and the integrating piston 54 will be prevented from settling.

After the main contacts open during the second operation the second measured quantity of hydraulic fluid will be delivered by the pump piston 25 as the plunger 19 rises. In addition, the opening of the main contacts will release the clapper 72 so that this measured quantity of hydraulic fluid will again raise the integrating piston 54 until the groove 70 between the uppermost two large diameter washers 56 is opposite the inner end of the slide valve rod 66. This will allow only partial movement of the slide valve members 63 and 64 toward the right as seen in FIG. 5 so that member 64 will be disposed at the intersection of ducts 6 1 and 82. As a result, the only vent for the dashpot 37 will be through the orifice 86a so that the descent of the plunger 19 into dashpot 37 will be retarded whereby the third opening operation of the recloser will be time delayed. The piston :19 will continue its downward movement at a retarded rate until a transverse passage 90 therein is brought into communication with the recess 79 whereupon the dashpot 37 is vented through the passage 90 and a vertical passage 91 which opens into a recess 92 in the upper end of plunger '19.

It can be seen that because all of the remaining washers and the piston 54 have a large diameter all of the subsequent opening operations will also be time delayed. After a predetermined number of such time delayed operations the upper end of the stem 28 will engage the lockout lever 29 and the re-closers main contacts will be locked open.

The speed of the return stroke of the plunger 19 will be governed by the rate at which hydraulic fluid is drawn into the dashpot 37 as the plunger 19 rises. Because the main contacts are open at this time and the clapper 72 is relaxed, the slide valve 60 will be in its position shown in FIG. 1 whereby orifice 86a and the outer end of duct 61 are blocked by slide valve member 64 wherein the only path for this fluid is through the orifice 86b so that this orifice controls the rate of rise of the piston '19.

In the above illustration of the operation of the recloser 10, it was set for two rapid and two retarded operations before lockout. This was accomplished by arranging small diameter washers 56 opposite the slide valve 60 during the initial two operations and large diameter washers 55 opposite this member during the final two operations. It can be seen, therefore, that by various combinations of large and small diameter washers, any combination of fast and slow operations can be achieved. Additional such washers 55 and 56 for this purpose may be carried above the piston 54.

FIG. 6 shows an alternate embodiment of the instant invention wherein hydraulic means is provided for urging the slide valve 60 into engagement with the integrating piston 54. This includes a conduit member which connects the passages 61 and 83 in casing 31. Thus, the left side of the piston valve 64 will be subjected to the hydraulic pressure resulting from the egress of hydraulic fluid from cylinder 37. While the right side of piston valve 64 will also be subjected to this hydraulic pressure, the area of the right side will be substantially smaller than the area of the left side of piston valve 64 as a result of the stem 66. As [a result, there will be a net force on piston valve 64 toward the right, as viewed in FIG. 6, each time the magnetic plunger 19 descends on this force will be suflicient to overcome spring 76 and move the end of stem 66 into engagement with the integrating piston 54.

Provision may also be made in conduit 115 for the safety with respect to a particular type of recloser, it is not intended to be limited thereby but only by the scope of the appended claims.

I claim:

1. A liquid immersed reclosing circuit interrupter including switch means in circuit with the system being protected, switch opening means including overcurrent responsive means coupled to said system, switch closing means, normally inactive lockout means adapted to be rendered efiective for preventing the closure of said switch means, a hydraulic cylinder, an integrating piston disposed in said cylinder, said piston being urged toward one end of said cylinder, means operable between each switch opening and reclosing operation to advance said piston an incremental distance toward said lockout means, said piston being engageable with said lockout means after a predetermined number of operations to render said lockout means effective, said piston having a plurality of indexing means, and means operable in response to an overload current in said system for movement into engagement with the one of said indexing means corresponding to the previous advancement of said piston for preventing movement of said piston toward the one end of said cylinder when overload current flows in said system, said last named means being inoperable in the absence of overload current in said system to remain in engagement with said piston.

2. The circuit interrupter set forth in claim .1 wherein said last mentioned means includes electromagnetic means responsive to overload current in said system for moving a member into engagement with said piston.

3. The liquid immersed reclosing circuit interrupter set forth in claim 1 wherein said overcurrent responsive means includes a coil in circuit with said system and a magnetic plunger movable from an initial position toward said coil upon the occurrence of an overload in said system to open said switch means, and wherein said switch closing means is operable to return said magnetic plunger to its initial position after a switch opening operation and to close said main switch means.

4. A liquid immersed reclosing circuit interrupter including switch means in circuit with the system being protected, resilient means urging said switch means toward a closed position, switch opening means including a coil in circuit with said system and a magnetic plunger engaging said resilient means and movable from an initial position toward said coil upon the occurrence of an overload in said system to open said switch means in opposition to said resilient means, said resilient means being operable to return said magnetic plunger to its initial position after a switch opening operation to close said main switch means, normally inactive lockout means adapted to be rendered effective for preventing the closure of said switch means, a hydraulic cylinder, an integrating piston disposed in said cylinder and urged toward one end thereof, means operable by said resilient means between each switch opening and reclosing operation to advance Sittld piston an incremental distance toward said lockout means, said piston having a plurality of indexing means, and means operable in response to an overload current in said coil for movement into engagement with the one of said index means corresponding to the previous advancement of said piston for preventing movement of said piston toward the one end of the cylinder when overload current flows in said coil.

5. A liquid immersed reclosing circuit interrupter including switch means in circuit with the system being protected, switch opening means including a cylinder having relief port means, a coil in circuit with said system and a magnetic plunger movable into said cylinder to open said switch means upon the occurrence of an overload in said system, means operable to return said magnetic plunger to its initial position after a switch opening operation to close said switch means, operation counting means operable between each switch opening and reclosing operation for advancement in a step-by-step manner and having a first and second plurality of indexing means, an indexing member movable into engagement with one of said first plurality of indexing means during initial occurrences of overload in said system and with one of said second indexing means upon subsequent occurrences of overload, said indexing member being effective to block at least part of said relief port means when in engagement with said second plurality of indexing means so that the movement of said plunger is time-delayed, said indexing member bein inefiective to block said relief port means when in engagement with one of said first indexing means so that the initial switch opening opening operations will be rapid.

6. The circuit interrupter set forth in claim 5 wherein said operation counting means comprises a second cylinder and an integrating piston disposed in said cylinder.

7. The circuit interrupter set forth in claim 6 wherein biasing means urges said integrating piston toward one end of said second cylinder, and including normally inactive lockout means adapted to be rendered effective for preventing closure of said switch means, said lockout means being actuable upon a predetermined advancement of said integrating piston, the engagement between said indexing mean-s und said integrating piston also being operative to prevent movement of said piston when overload current flows in said system.

8. The repeating circuit interrupter set forth in claim 7 wherein said first and second indexing means comprises a plurality of elements removably mounted on said piston whereby the number of each may be varied so that the number of rapid and retarded operations may be correspondingly varied.

9. The repeating circuit interrupter set forth in claim 8 wherein said indexing member comprises a slide valve and said first and second indexing elements have difierent relative sizes, said slide valve member being disposed in a passage opening into said second cylinder wherein advancement of said piston will move different ones of said elements into alignment with said passage so that the position of said slide valve member relative to said cylinder during a switch opening operation is governed by the advancement of said piston.

10. A liquid immersed reclosing circuit interrupter including switch means in circuit with the system being protected, resilient means urging said switch means toward a closed position, switch opening means including a first cylinder having discharge orifice means, a coil in circuit with said system and surrounding said first cylinder and a magnetic plunger engaging said resilient means and movable into said first cylinder upon the occurrence of an overload in said system to open said switch means in opposition to said resilient means, said resilient means being operable to return said magnetic plunger to its initial position after a switch opening operation to close said main switch means, first and second relief port means connected to said discharge orifice means, normally inactive lockout means adapted to be rendered effective for preventing the closure of said switch means open after a predetermined number of switch opening operations, a second cylinder, an integrating piston disposed in said second cylinder, means operable by said resilient means between each switch opening and reclosing operation to advance said piston an incremental distance toward said lockout means, said piston having a first and second plurality of indexing means, an indexing member being successively movable into engagement with one of said first plurality of indexing means during initial occurrences of overload in said system and with one of said second indexing means upon subsequent occurrences of overload, said indexing member being effective to block at least one of said first and second relief port means when in engagement with said second plurality of indexing means so that the descent of said plunger and said first cylinder is time-delayed, said indexing means being inefiective to block said relief port means when in engagement with one of said first indexing means so that the initial switch opening operations will be rapid.

11. The repeating circuit interrupter set forth in claim 10 wherein said integrating piston is urged toward one end of said second cylinder and the engagement between said indexing means and said piston also being operative to prevent such movement of said piston when overload current flows in said system.

12. A liquid immersed reclosing circuit interrupter including switch means in circuit with the system being protected, resilient means urging said switch means toward a closed position, switch opening means including a first cylinder having discharge orifice means, a coil in circuit with said system and surrounding said cylinder and a magnetic plunger engaging said resilient means and movable into said first cylinder upon the occurrence of an overload in said system to open said switch means in opposition to said resilient means, said resilient means being operable to return said magnetic plunger to its initial position after a switch opening operation to close said main switch means, first and second relief port means connected to said discharge orifice means, normally inactive lockout means adapted to be rendered effective for preventing the closure of said switch means open after a predetermined number of switch opening operations, a second cylinder, an integrating piston disposed in said second cylinder, means biasing said piston toward one end of said second cylinder, means operable by said resilient means between said switch opening and said switch reclosing operations to advance said piston an incremental distance away from the one end of said second cylinder and toward said lockout means, said piston including a plurality of relatively large beveled washers adjacent the one end of said second cylinder and a plurality of small diameter washers intermediate its ends, a slide valve 3 member disposed in said passage, means coupling said slide valve to said plunger for movement of said member into engagement with said large beveled washers during initial occurrences of overload in said system and into engagement with said small beveled washers upon subsequent occurrences of overload, said slide valve member being eifective to block at least one of said first and second relief port means when in engagement with said large beveled washers so that the descent of said plunger and said first cylinder is time-delayed, said slide valve member being ineffective to block said relief port means when in engagement with one of said small diameter Was-hers so that the initial switch opening operations will be rapid.

13. he circuit interrupter set forth in claim 12 Wherein the engagement between said slide valve member and any of said washers being operative to prevent movement of said piston toward the one end of the second cylinder when overload current flows in said system.

References Cited by the Examiner UNITED STATES PATENTS 2,442,477 6/ 1948 Wallace 20089.4 2,656,433 10/ 1953 Edwards 20089.4 2,769,054 10/1956 Edwards ZOO-89.4 2,777,031 1/ 195 7 Wallace 20089.4 2,891,121 6/1959 Date 20089.4 3,056,006 9/ 1962 Froland 200-97 References Cited by the Applicant UNITED STATES PATENTS 2,442,477 6/ 1948 Wallace. 2,656,433 10/ 1953 Edwards. 2,769,054 10/ 1956 Edwards. 2,777,031 l/ 1957 Wallace. 2,891,121 6/1959 Date. 3,056,006 9/1962 Froland.

BERNARD A. GILHEANY, Primary Examiner.

ROY N. ENVALL, ]R., Assistant Examiner. 

1. A LIQUID IMMERSED RECLOSING CIRCUIT INTERRUPTER INCLUDING SWITCH MEANS IN CIRCUIT WITH THE SYSTEM BEING PROTECTED, SWITCH OPENING MEANS INCLUDING OVERCURRENT RESPONSIVE MEANS COUPLED TO SAID SYSTEM, SWITCH CLOSING MEANS, NORMALLY INACTIVE LOCKOUT MEANS ADAPTED TO BE RENDERED EFFECTIVE FOR PREVENTING THE CLOSURE OF SAID SWITCH MEANS, A HYDRAULIC CYLINDER, AN INTEGRATING PISTON DISPOSED IN SAID CYLINDER, SAID PISTON BEING URGED TOWARD ONE END OF SAID CYLINDER, MEANS OPERABLE BETWEEN EACH SWITCH OPENING AND RECLOSING OPERATION TO ADVANCE SAID PISTON AN INCREMENTAL DISTANCE TOWARD SAID LOCKOUT MEANS, SAID PISTON BEING ENGAGEABLE WITH SAID LOCKOUT MEANS AFTER A PREDETERMINED NUMBER OF OPERATIONS TO RENDER SAID LOCKOUT MEANS EFFECTIVE, SAID PISTON HAVING A PLURALITY OF INDEXING MEANS, AND MEANS OPERABLE IN RESPONSE TO AN OVERLOAD CURRENT IN SAID SYSTEM FOR MOVEMENT INTO ENGAGEMENT WITH THE ONE OF SAID INDEXING MEANS CORRESPONDING TO THE PREVIOUS ADVANCEMENT OF SAID PISTON FOR PREVENTING MOVEMENT OF SAID PISTON TOWARD THE ONE END OF SAID CYLINDER WHEN 